package j20251103;

public class Solution1 {
    boolean[][] vis;
    int[] dx={0,0,1,-1};
    int[] dy={1,-1,0,0};
    int m,n,ret,step;
    public int uniquePathsIII(int[][] grid) {
        m=grid.length;
        n=grid[0].length;
        vis=new boolean[m][n];
        int bx=0,by=0;
        for(int i=0;i<m;i++){
            for(int j=0;j<n;j++){
                if(grid[i][j]==0){
                    step++;
                }
                if(grid[i][j]==1){
                    bx=i;
                    by=j;
                }
            }
        }
        step+=2;
        vis[bx][by]=true;
        dfs(grid,bx,by,1);
        return ret;
    }
    public void dfs(int[][] grid,int i,int j,int count){
        if(grid[i][j]==2){
            if(count==step){
                ret++;
            }
            return;
        }

        for(int k=0;k<4;k++){
            int x=i+dx[k];
            int y=j+dy[k];
            if(x>=0&&x<m&&y>=0&&y<n&&!vis[x][y]&&grid[x][y]!=-1){
                vis[x][y]=true;
                dfs(grid,x,y,count+1);
                vis[x][y]=false;
            }
        }
    }
}
